Lithium levels with once-daily dosing

[SpongeBob DoctorPants]

When is the ideal time to check lithium levels on a patient who takes it once a day? I know it's best to get a trough level, typically done right before the next dose. But I don't know if this only applies to BID or TID dosing, or if it would also apply to once-daily dosing.

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[michaelrack]

I don't have a source, but seem to remember hearing that you could still check morning levels (for once/day qhs dosing), with the desired level being about 10 % than with multiple times per day dosing.

 

[psychattending]

Lithium levels are 12 hours post dose (i.e. half of T1/2), which is why they are done in the morning after the evening dose.

 

[slappy]

When is the ideal time to check lithium levels on a patient who takes it once a day? I know it's best to get a trough level, typically done right before the next dose. But I don't know if this only applies to BID or TID dosing, or if it would also apply to once-daily dosing.

It depends on why it's a once-daily dosing. Typically, I do this for patients in renal failure. In this case, 20-24 hours post-dose is the right time to draw the level. 12-hour post dose is typically about 30% higher.

 

[SpongeBob DoctorPants]

Thanks for the replies, everyone. This is very helpful.

12-hour post dose is typically about 30% higher.

This is consistent with a study I found online, in which they compared labs at 12 hours vs. 24 hours for once-daily dosing, and it was found that the 12-hour lab values are 1.3 times the 24-hour values. It was not mentioned in that article, however, which of those labs should be used for determining the actual lab value to compare with the reference range.

 

[psychattending]

Thanks for the replies, everyone. This is very helpful.


This is consistent with a study I found online, in which they compared labs at 12 hours vs. 24 hours for once-daily dosing, and it was found that the 12-hour lab values are 1.3 times the 24-hour values. It was not mentioned in that article, however, which of those labs should be used for determining the actual lab value to compare with the reference range.

It would be the 12-hour value as that is how most of the studies looking at level and response/side-effects were done (i.e. am lab with holding of the am dose). Happy to provide additional info off-line if you need it.

 

[nexus73]

I say lithium (lithobid or sr) should be dosed qhs only, with level checked 12 hrs later. Better patient adherence and lower risk of renal side effects. I’ve had good luck with this clinically.

 

[Merovinge]

I say lithium (lithobid or sr) should be dosed qhs only, with level checked 12 hrs later. Better patient adherence and lower risk of renal side effects. I’ve had good luck with this clinically.

I'm trying to wrap my head around lower risk of renal SE for QHS vs BID dosing of lithium ER. Can you explain this to me further or link a citation? Thanks!

 

[PistolPete]

I say lithium (lithobid or sr) should be dosed qhs only, with level checked 12 hrs later. Better patient adherence and lower risk of renal side effects. I’ve had good luck with this clinically.

This is true and exactly why I only use immediate-release Lithium and dose it at bedtime. Using once-a-day dosing and avoiding the slow-release formulation only causes a once-a-day peak, spares the nephron and there eliminates or delays the onset of diabetes insipidus.

 

[nexus73]

I'm trying to wrap my head around lower risk of renal SE for QHS vs BID dosing of lithium ER. Can you explain this to me further or link a citation? Thanks!

I'm not the smartest psychiatrist out there, but here's a couple references.

Lithium in Bipolar Disorder: Optimizing Therapy Using Prolonged-Release Formulations

An updated review of the optimal lithium dosage regimen for renal protection. - PubMed - NCBI

This is true and exactly why I only use immediate-release Lithium and dose it at bedtime. Using once-a-day dosing and avoiding the slow-release formulation only causes a once-a-day peak, spares the nephron and there eliminates or delays the onset of diabetes insipidus.

Regarding the regular release vs sustained release, I'd expect a lower peak level with the SR because it's being absorbed at a slower rate. It's not clear to me whether having a lower peak level is easier on the kidneys (SR would have lower peak), or if having a higher peak of short duration, but lower overall levels between doses (immediate release) is safer long term. Interesting.

 

[PistolPete]

I'm not the smartest psychiatrist out there, but here's a couple references.

Lithium in Bipolar Disorder: Optimizing Therapy Using Prolonged-Release Formulations

An updated review of the optimal lithium dosage regimen for renal protection. - PubMed - NCBI


Regarding the regular release vs sustained release, I'd expect a lower peak level with the SR because it's being absorbed at a slower rate. It's not clear to me whether having a lower peak level is easier on the kidneys (SR would have lower peak), or if having a higher peak of short duration, but lower overall levels between doses (immediate release) is safer long term. Interesting.

Per our psychopharmacology consultants at the State hospital, immediate release is much better on the kidneys than slow release. My guess is the shorter duration and higher peak is better than longer duration/lower peak on the kidneys. If I can find a reference article I'll post it.